The fabrication of masters, usually called “mastering”, consists of integrating on an intermediary support personalization information intended for industrial pressing optical disks. The quality of the master determines the quality of the final product. This operation is performed in the state of the art by long, painstaking solutions, employing complex equipment, the employment of which is often centralized with specialized suppliers who perform for multiple industrial corporations the pressing of personalized masters. These masters are then used for pressing polycarbonate disks. They are in the form of nickel wafers bearing the information to be reproduced in the form of microreliefs forming by molding disks of approximately 150 nanometers in thickness and 0.4×0.3 μm for DVDs and 0.8×1 μm for CDs.
WO 99/18572, for example, describes a method for the fabrication of a pressing master for production of optical disks. This method consists of applying a photoresist on the plate of a pressing master, then of structuring the photoresist film applied in this manner. This structuring step consists successively of sublimating locally and heating the photoresist film prior to subjecting it to a supplementary exposure step in the range of ultraviolet to short wavelength, prior to its final thermal treatment. The effective dose of this supplementary exposure step ranges between 4·10−4 and 5·10−2 J/cm2.
Also known are solutions for disk etching on a unit basis. WO 00/08643 describes, for example, a pre-etched substrate for a memory disk that can be recorded by a magnetic, magneto-optical or optical phase transition stress. This pre-etched substrate comprises a support having at its surface a surface layer made of a reflective material and making it possible to obtain an optically polished surface and at least one recordable surface. These layers comprise a succession of micropits and/or grooves representing a preforming signal.
It would therefore be advantageous to provide a method for the fabrication of masters compatible with use for industrial pressing by polycarbonate molding and not merely by a unit basis etching, while simplifying the fabrication of the masters and avoiding the recourse to an initial support made of glass and multiplication of the steps that results therefrom.